The Best Sleep-Tracking App

We’ve updated which phones SleepScore is currently compatible with. In response to reader comments, we’re long-term testing Sleep as Android to compare its sleep advice with SleepScore’s.

Your guide

Joanne Chen

After roughly 60 hours of research—including interviews with seven sleep researchers—and a month testing sleep-tracking apps, we recommend SleepScore. It’s more intuitive and provides deeper sleep analysis and advice than other apps. Although it doesn’t work on many Android phones, we still recommend SleepScore because it’s more transparent about the science behind its app.

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We think SleepScore will do the best job of helping you improve your sleep. In our test group, it’s the only app that both allows you to set sleep goals and gives actionable advice for reaching them. It also provides more-detailed sleep-stage data than most other apps, and its smart alarm did a pretty good job of helping us feel less groggy. The free version provides general sleep advice and a record of your sleep for seven days at a time. For $50 a year (or $6 per month), it will track and record your sleep reasonably accurately for the long term and help you create a path for improvement. As of October 2018, SleepScore works only on newer iPhones and certain Samsung Galaxy phones, but the company plans to expand to other Android phones. If SleepScore doesn’t work on your phone, we recommend using Sleep Cycle or Sleep as Android instead.

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We like Sleep Cycle almost as much as SleepScore, but it falls short because the company is less transparent about its research and the app doesn’t give much detailed sleep-stage data. Unlike SleepScore, it won’t show when you fell asleep, or for how long you were in light or REM sleep. It also won’t give you any advice for improving sleep. But this app’s clean graphs make it easy to see general sleep trends—which may be all you need to understand your sleep patterns—and it keeps your notes about daily diet, exercise, weather, and anything else that might impact sleep directly on the app (SleepScore makes you log into its website to see those notes). We also love that it has more than a dozen smart alarm sounds and lulling sleep sounds to choose from—so getting up and going to bed feels a lot more pleasant.

Why you should trust us

As a health journalist, I’ve followed the scientific research on sleep for more than a decade. For this guide, I interviewed product specialists and brand executives in the sleep-tracking field, sleep doctors who’ve done their own sleep-tracking experiments either formally or informally, as well as a computer scientist specializing in behavior tracking. I also slept with the tracking apps myself for at least seven nights and compared them with the sleep trackers in two fitness bands (the Fitbit Versa and Garmin Vívosport) and a couple of apps (Sleep++ and AutoSleep) for the Apple Watch. Three fitness-tracker-wearing colleagues also helped test the apps.

Last but perhaps not least, I’m personally familiar with professional-grade sleep tracking. I spent a restless night in a sleep clinic with my then-toddler son when he was suspected to have sleep apnea (he did). A few years before that, I had shooed my husband off to the same clinic to have his snoring checked out (and it turned out he has sleep apnea, too.)

Who should get this

Everyone sleeps, but sleep trackers aren’t for everyone. Personal sleep tracking is a new science—the app makers haven’t nailed accurate readings yet, and they’re often not great at telling a typical user what to do with the results. In fact, as W. Chris Winter, MD, author of The Sleep Solution: Why Your Sleep Is Broken and How to Fix It, told me, quoting a pessimistic colleague, “The best thing that trackers have allowed us to do is admire our problems.”

I wouldn’t say I like “admiring” my problems, but I do like to know where I stand—and, considering the popularity of health trackers, plenty of others feel the same way. That said, these apps work best for people who are only casually looking for clues as to how they might sleep better at night and emerge the next day feeling energized. If you’re an elite athlete or marine officer or airline pilot whose sleep analysis could make or break your career, these apps are not for you. (But you knew that already.) If you think you might have sleep apnea and are hoping that your phone will save you from a night in a sleep clinic, these are also not for you. (Talk to your doctor.)

Skip sleep trackers if less-than-stellar results tend to upset you. In fact, there’s a term for that: orthosomnia—a preoccupation with perfecting one’s sleep data. Kelly Baron, PhD, a clinical psychologist now at the University of Utah, coined it when she noticed a spike in patients riddled with anxiety about their supposedly poor sleep duration and quality. If this is you, you’re probably better off relying more on how you feel throughout the day to figure out how well you slept. But if you enjoy geeking out on exploring your quantified self, come what may, sure, give these apps a go. Many offer free trials, so you have nothing to lose (except sleep).

These apps work best for people who are only casually looking for clues as to how they might sleep better at night and emerge the next day feeling energized.

There are all kinds of sleep trackers, including standalone devices that go on your nightstand or under your mattress; standalone wearables, such as a mask or ring; and features built into fitness trackers and smartwatches. We focused on apps because they’re accessible and relatively inexpensive, which makes them far more appealing to most people.

How sleep trackers work

We tested a variety of sleep-tracking devices, including (from left to right) an Apple Watch, apps for iPhones and Android, and a FitBit. Photo: Rozette Rago

Tracking sleep at home is hard. In fact, “It’s like trying to track an earthquake,” said Thomas Penzel, PhD, research director of the Interdisciplinary Center of Sleep Medicine at Charité University in Berlin. Just as you can’t sit inside the earth and watch tectonic plates shift, you can’t directly peer into your own brain as you’re sleeping. So you need proxies. In a sleep lab, scientists use medical-grade equipment and sensors to record brain activity, eye movements, body movements, heart rate, oxygen intake, and more. This process, called polysomnography, is the most reliable method of sleep tracking.

Unfortunately, currently available sleep trackers designed for home use can’t read brain waves and eye movements, which most reliably track stages of sleep, so instead they guesstimate based on less accurate signs. The current technologies include:

Movement tracking: Accelerometers—common in fitness trackers and other wearables—interpret stillness as sleep and movement as wakefulness. But they’re not very accurate when used alone because the tracker may think you’re asleep when you’re lying still staring at the ceiling. If you toss and turn a lot in your sleep, it could also think you’re awake. That’s why it’s typically paired with other technologies, such as optical heart-rate monitoring, when used for sleep tracking.

Sound detection: Phone apps using this technology analyze the sound of various movements that occur in the different sleep stages. For instance, when the app “hears” less movement it assumes that you’re in deep sleep; when it “hears” more movement, it assumes you’re in light sleep. This means it can track from your nightstand instead of your mattress.

Sonar: This is the same technology that helps bats and submarines get around. The phone’s speakers emit sound waves at frequencies inaudible to humans. These waves deflect off of your chest as it moves while breathing and the phone’s microphone picks up these waves. Because the rhythm and depth of your breath changes as your brain shifts from various stages of sleep, the shape of the deflected waves vary over the course of the night, and the app’s algorithms use that information to analyze your sleep.

Optical heart-rate monitoring: You’ll find this in fitness trackers and the Apple Watch. Tiny LEDs in your band shine a light through your skin to capture blood flow; as the rate changes, so does the light that reflects back to your device; the device then combines that information with your movement data to deliver your sleep report. In our tests, the results from wearables were as varied as those of the phone apps, but some researchers believe there’s high potential for improvement. Because devices (fitness bands, smartwatches) using optical heart-rate monitoring are on your body, said Penzel, “in principle they should be more accurate as they develop better algorithms, but that takes time.”

It’s hard to say which technology is best. “There’s different implementations and environments,” explained Jeff Huang, PhD, a Brown University computer scientist specializing in human-computer interaction, “so I’d hesitate to say that one technology is straight up better than another without an extensive study.” Sound sensing could be great for someone in a very quiet room who doesn’t snore, he said. Sonar may work with someone with consistent breathing patterns. Accelerometers might be useless on a foam mattress, but perform well on a wearable.

The final reading depends both on how well an app measures the data and how well the company’s algorithm interprets that data. But even then, two apps using the same technology can yield very different sleep reports, explained Michael T. Smith Jr., PhD, founder of the Behavioral Sleep Medicine Program at the John Hopkins School of Medicine. Further complicating matters, these readings evolve over time. As Smith said, “Your first sleep is the least accurate. The more you use it, the more data it collects, the more helpful it can become.”

All in all, the accuracy and precision of personal sleep-tracking devices still leave much to be desired, regardless of the device or the technology. But that doesn’t mean they’re not useful. After all, sleep labs have their own limitations. “One night in a lab is in no way representative of our sleep life; it’s one night of sleep in a strange sleep environment hooked up to a lot of equipment,” said Nathaniel Watson, MD, co-director of the University of Washington Medicine Sleep Center and a neurologist who developed the sonar-based technology at the university before it was licensed to SleepScore. At least the apps, he said, may help us “understand sleep in the wild.” And as Smith, who advised Fitbit on its sleep advice, pointed out, “If you’re interested in patterns, it’s good at that and that might be what you need to set goals for change and to feel better.”

How we picked and tested

When it comes to sleep-tracking apps, it’s easy to get caught up about accuracy. But the ultimate goal isn’t to perfectly track your sleep; it’s to track trends in your sleep so that you can better understand and improve it. To make that happen, several other features are also crucial. Here’s what we looked for in the apps, in order of importance:

Ease of use: We wanted to know exactly where to tap to set the alarm (as opposed to swiping from screen to screen, frantically trying to set things up), how to tell if it’s tracking already, how to shut off the alarm, and so on. We also preferred apps we could set on a nightstand as opposed to on the bed.

Ease of interpretation: Multicolored graphs look impressive but they’re useless if they require a doctorate in statistical analysis to understand. Clearly labeled X and Y axes and reports in everyday English are a huge help at 5:30 in the morning.

Actionable advice: Without solid direction as to how to get better sleep, the apps are just platforms for spitting out graphs. “If a pedometer registers 1,400 steps at 2PM, you know exactly what you need to do—go out for a walk,” said Winter. “But when a sleep tracker says you’ve had too little deep sleep, most people aren’t sure what to do with that.” We looked for trackers that give advice or put the data in context: for instance, reminding people to get to bed more consistently or letting them know when they may be sleep deprived.

Accuracy and precision: We looked for apps that could give reasonably good readings for when we fell asleep, when we woke, how often we woke during the night, and when we entered various sleep stages. Ideally, the app could provide the reading down to the minute. Realistically, most apps don’t do this—and you don’t really need them to. Explained Winter, “If you simply want to get an idea whether, say, you get better sleep at your place or your boyfriend’s, then it doesn’t have to be that precise.” For this reason, though accuracy and precision were an important consideration, it wasn’t the top concern.

Useful extras: We also chose apps that offer a smart alarm, which wakes you up during light sleep in an interval of your choosing, so you feel less groggy; alarm sounds beyond the usual jolting phone ring; and, in some cases, lulling snooze sounds (like Sleep Sheep for grown-ups!).

It was impossible to test all of the apps on the iTunes store and Google Play, so we started by choosing the most talked-about and downloaded apps that also had ratings of more than four out of five stars. We then checked that the apps took privacy and security issues seriously—that the data isn’t shared with third parties, that the info is encrypted, and that the data they use from you to inform their research and improve their product is aggregated and anonymous. Keep in mind, however, that keeping aggregate data completely private is really difficult, as explained in this FTC blog post. It’s always smart to be vigilant, just as you would with other health trackers: don’t share your info on social media without understanding the privacy policy of those third-party platforms, and, if you cancel your app subscription, email customer service to delete your information completely.

We also confirmed that each has a way to export that data (reason being, companies come and go, and you wouldn’t want your information to disappear with it), and we sent out a few emails to customer support to see how responsive they were. We selected four apps to test: Pillow, Sleep as Android, SleepScore, and Sleep Cycle.

I spent eight days testing them all at the same time, and I also tested some of them individually a few more days before or after the pilot test. I played around with the snooze sounds and smart alarms (all offered a similar selection; I was especially fond of waking up to chirping birds). I wore the Fitbit Versa, Garmin Vívosport, and Apple Watch on the same wrist, to find out if getting a phone app is worth doing if you already have a fitness tracker.

Because I couldn’t exactly scurry up PSG equipment for my bedroom, Winter suggested I test the accuracy of the apps and wearables against a sleep diary. Of course, I wouldn’t be able to record the times I unconsciously woke up and for how long, but for the times I did knowingly wake up, I could mark them in my diary and compare them with the various app readings. I used the template (PDF) downloaded from theAmerican Association of Sleep Medicine website. In it, I noted whether I had alcohol, coffee, or exercise; my bedtime; when/if I woke up in the middle of the night; and when I woke up for good. Only once did I consciously wake up from a dream (aka, REM sleep); I marked that too.

The results, as you can see here from one typical night, were presented in a variety of ways:

From left: SleepScore, Sleep Cycle, Pillow, and Sleep as Android.

Each of them reported a different set of variables, so it’s hard to compare all of the results. But by juxtaposing, say, sleep quality or deep sleep, in the apps that offer it, you can get an idea how all-over-the-board they are:

The average amount of time I spent in deep sleep over five days—according to three phone apps.

I didn’t focus on the discrepancies between the different readings for specific variables, like sleep quality, because it’s not the absolute results retrieved over the course of one night that matters, but trends you glean from many nights. I kept that in mind as I made my top two picks, which then underwent further testing by three colleagues, who also tested them against their favorite wearables. After a week, we compared notes to arrive at a top pick.

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A sleep tracker shouldn’t just track sleep, it should help you improve it—and SleepScore does this better than the others we tested. It was the easiest to set up, gave the clearest analysis of sleep trends, and was the only app we tried that gave actionable advice for reaching specific sleep goals. We found it to be more accurate than the other apps, and the most transparent about the research.

Setup was efficient and user-friendly. The app led me through the process in such a way that I didn’t feel the need to watch or, on subsequent nights, rewatch an instructional video (as I resorted to with Pillow and Sleep as Android). It was obvious where to tap to set the alarm, at which point a few questions about my day (caffeine? exercise?) automatically popped up. Upon answering, the tracker automatically started tracking.

SleepScore’s analysis of my sleep was also easier to understand. When the smart alarm woke me, the app greeted me with a cheerful “Good morning, Joanne!” on its screen, followed by my overall SleepScore, as well as a “mind” and “body” score, among other things. I usually woke up before the alarm went off (as moms with young kids often do), but on the rare days that I had at least six uninterrupted hours of sleep, I did feel less jolted awake when the smart alarm kicked in, though I think the gentle sound of it helped as much as the timing.

The screen alerts you to tap on the “aura” around the number to find out how the numbers were calculated. I didn’t have to guess what the scores or any of the terms used in the app meant—unlike with Sleep Cycle and Sleep as Android—nor did I have to decipher a graph or (as with Pillow) deal with percentages. It was all laid out, plain as day, in a neat list: sleep duration, time to fall asleep, light sleep, deep sleep, REM sleep, and wake time, with the units expressed in simple hours and minutes. It also tells you how many times you woke up during the night and when exactly you were experiencing each phase of sleep. For people who love data, SleepScore offers about as much as Pillow, and more than Sleep Cycle and Sleep as Android.

The premium version of SleepScore—at $50 per year or $6 per month—was also the only phone app we tested that allowed me to set a goal and advised me on how to achieve it. I selected “perfect your sleep” as my goal, but there were six others to choose from, including “sleep longer,” “wake up less,” and “sharpen my mind.” This, in turn, placed me on an “Improve your sleep hygiene path” and led me to a list of hygiene-improving strategies, such as avoiding heavy or high-acidity meals. None of the advice was particularly earth-shattering, but it was nice to be given some direction.

So did Sleep Score’s advice improve my sleep? Not yet. It takes weeks to learn good habits and break old ones. The app tries to keep you motivated by providing advice and awarding you with “sleep stars” (the equivalent of virtual “stickers” in a kid’s educational video game) when you hit a milestone. I earned a star when I managed seven straight days of sleep tracking, for instance, but you can also get rewarded for bedtime consistency and sleep duration. Still, you’ve got to be personally motivated. After all, hoping to improve on sleep with an app is not unlike hoping to exercise more or lose weight with an app. You have to be especially self-motivated and committed to it—because, unlike with a real coach, it won’t yell at you or make you feel bad when you ignore the advice.

SleepScore’s free version doesn’t provide customized advice or a record of personal trends, and it shows you only the last seven days of sleep, so we think the premium version is worth shelling out for. Although our runner-up, Sleep Cycle, offers many helpful features, it’s not designed to provide any advice, regardless of upgrade.

Although I didn’t experience this, Sleep Score does, on occasion, make product recommendations for improving sleep. For instance, if the app were to notice that it consistently takes you a long time to fall asleep, it might suggest a specific pair of blue-light-filtering glasses and provide a link to buy. (Sleep Score’s scientific advisers and testers independently test and assess all products recommended; in some cases, SleepScore might collect a cut of the cost as part of the way to fund the app and its research.)

Hoping to improve on sleep with an app is not unlike hoping to exercise more or lose weight with an app. You have to be especially self-motivated and committed to it.

As far as accuracy is concerned, I was happy to find that I could often corroborate my middle-of-the-night awakenings on the app—which uses sonar—with the chicken-scratched times in my sleep diary. Other apps picked up on my awakenings, but none attempted to be as precise as SleepScore, which was often only a few minutes off from my sleep diary. Of course, I didn’t really need to know exactly at what minute of the hour I woke up, but, being sort of a data geek, I appreciate the effort.

A “126” scrawled on my diary (right) corresponded to a 1:24 a.m. wake time in SleepScore’s “Sleep Graph” screen (left).

The app launched only in June 2018, but its technology (developed by academic researchers before it was licensed to SleepScore) is the result of more than 12 years of scientific research. Per the recommendations of the American Academy of Sleep Medicine, SleepScore is one of the few companies that validates its results in articles that are readily available on its website. Its latest white paper, for instance, reported that the app can correctly detect a wake when you are actually awake 87 percent of the time compared with PSG. It has a tougher time tracking light sleep, being only 64 percent accurate. These are not independent studies, so take them with a grain of salt, but we appreciated the transparency. When I emailed the other makers, I was told that they indeed continually work on their algorithms for accuracy, though any studies they did to test accuracy against PSG wasn’t immediately available to the public (or me, for that matter).

SleepScore was also the only app we tested that provides bios of its scientists—Watson, two other academic researchers, plus Mehmet Oz (yes, that Dr. Oz), who is also an equity investor. (Full disclosure, I briefly freelanced at his eponymous magazine before it folded, though I’ve never met him.)

Flaws but not dealbreakers

As of October 2018, SleepScore works only on a limited number of phones, mostly Samsung Galaxy models and the iPhone 6 or later. When we asked the company about this, reps explained that because the app is dependent on a phone’s speaker and microphone, the company tests the app on each specific phone model for accuracy before supporting that phone. Given that the app launched only in June 2018 and that there are so many Android phones available, the company still has some ground to cover. As of this writing, among Android phones the app works on the Samsung Galaxy S7 Edge and the Samsung Galaxy S6, S7, S8, and S8+. The company plans to expand the app’s compatibility with additional phones, including the Samsung Galaxy S9, the Samsung Galaxy S9+, the Samsung Galaxy Note 8, and the Google Pixel 2 XL.

Unlike the other apps we tried, SleepScore doesn’t yet allow you to see how your lifestyle habits (alcohol and caffeine intake, exercise) correlate with your sleep right on the phone. Instead, you need to log on to its website. This is annoying.

It was also irksome that I couldn’t customize the list of lifestyle habits (which I could do with the other apps). I wanted it to tell me whether I wake up less in the middle of the night if I drank red or white wine, or if my REM sleep is whacked when binge-watching The Americans. However, the company tells me that correlations will be viewable on the phone by the end of the year, and there will be room for more customization on that lifestyle habits questionnaire I take before bed every night.

I wished it played soothing sleep sounds; I was getting rather spoiled by Sleep Cycle’s library of them, but I ultimately decided not to hold it against SleepScore, because it’s first and foremost a sleep tracker, not an adult Sleep Sheep.

Another downside: if you’re interested in knowing if you snore or grind your teeth, this app won’t figure that out by itself (though the other apps we tried will). You’ll have to incorporate its separate but free companion app, SnoreLab. You can download this and use it by itself, if you’re just interested in how you sound when sleeping.

Finally, a couple of online reviews complained of a high-pitched sound from the app. Neither I nor our testers perceived it, and if their pets heard it, they didn’t seem bothered by it either. Fortunately, with the free trial, you can give the app a go and move on to Sleep Cycle, our runner-up, if it turns out you have superhero-caliber hearing (which I was later told tended to be an issue with teenaged users).

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If you’re a more visual person and prefer a minimalistic interface, Sleep Cycle might be right for you. Sleep Cycle offers no sleep advice, and no explanation for its graphs or terminology on the phone. It offered less data than any of the apps tested, at least in terms of the specific stages of your sleep. But it’s as intuitive as SleepScore to set up and, perhaps because of its limited data output, it’s pretty easy to understand what’s going on in its sleep reports.

Sleep Cycle statistics and trends: Sometimes less is more.

What I really like about Sleep Cycle, though, is how neatly the sleep-lifestyle correlations are presented on-screen compared with all of the other apps. No need to go searching for it (as in the case of SleepScore, which keeps this data online). Simply tap on “Trends” and—voilà!—any factors you typed in the nights before, plus any Apple Health data, are automatically correlated with your sleep and shown in a way that even a third grader can figure out. For instance: Compared with how I slept at home in New York City, I slept worse when I was traveling for work, slightly better at my mom’s, and even better on vacation in the Catskills. Without putting together a single sentence, my app was telling me what I’ve been thinking all along: Maybe I really should move out to the ’burbs.

An excerpt from Sleep Cycle’s “Trends” section: What happens in Vegas (sleepwise).

We didn’t like that it took three weeks of persistent emails to get specific scientific information about the app. Unlike SleepScore, which provides research articles and bios of its scientists, Sleep Cycle doesn’t list any research on its site. For this reason, we felt that we couldn’t make it our top pick, despite its strong user reviews (as of publication it has 117,700 reviews, averaging 4.7 out of five stars, on the iTunes store).

Sleep Cycle uses a sound-sensing technology to assess your sleep. Compared with SleepScore, it seemed to catch fewer of my sleep-diary-recorded awakenings within a half-hour time frame, though it didn’t seem too off when it came to assessing my sleep as a whole. If I felt crappy in the morning because I couldn’t sleep, Sleep Cycle generally reflected that in its graph and score—which is perhaps the only information you actually need to glean patterns.

From left: a bad night’s sleep, with much of it spent in light sleep; a better night’s sleep with plenty of deep sleep.

Like SleepScore, Sleep Cycle is available on both iPhone and Android and it was pretty good at waking me up so that I wasn’t too groggy. Like SleepScore and Sleep as Android, you don’t have to put it on the mattress (which you must for Pillow). Because Sleep Cycle doesn’t require sonar, like SleepScore, it may also appeal to people who don’t like the idea of their phone transmitting sound waves onto them, though there’s no scientific evidence that anyone should be worried about that anyway.

Sleep Cycle’s no-cost option provides four groovy alarm rings (each sounds like relaxing yoga music) and will keep track of your sleep until eternity (theoretically). But it won’t provide extras, like 19 additional alarm sounds (including my favorite “Caribbean Cove”—birds on a beach) and 16 sounds to fall asleep to (such as “rain on a car roof,” “ocean waves,” and “medium wind”). Nor will it allow you to register your wake-up mood and that all-important ability to see how your lifestyle habits (aka “Sleep Notes”) correlate with your sleep. To me, that’s the fun of having an app, and therefore worth coughing up the $30 per year for the premium version. For this—and all of the apps, for that matter—you really need to go all in to get any meaningful benefit.

What about using a Fitbit, Apple Watch, or other wearable?

Fitness trackers and smartwatches will do a decent job at tracking your sleep, but they lack some of the smart features—like sleep sounds and alarm options—that can make phone apps appealing. Photo: Rozette Rago

If you already use a wearable with sleep-tracking capabilities, you may be perfectly happy sticking with what you have rather than buying a separate app to use on your phone. Wearables track your sleep automatically—no setup before bed. We tested the sleep-tracking on a Fitbit, Garmin, and Apple Watch (all of which use optical heart-rate monitoring technology and an accelerometer) against four apps. Although the wearables were often off compared with the apps, usually over-reporting sleep, they did give an accurate picture of sleep trends over time. This is something you’ll see as long as you consistently use the same device over the long term.

The biggest advantage of sleep-tracking phone apps over wearables are the extra features, like the lulling sleep sounds and the smart alarm.

The biggest advantage of sleep-tracking phone apps over wearables are the extra features, like the lulling sleep sounds and the smart alarm. Wearables can buzz you awake, which is a plus if you sleep with a partner with a different schedule, and nudge you to get ready for bed, just like it nudges you to “move”—but that’s generally it, sleep-wise. In addition, out of the apps we tried, only Fitbit (and Apple Watch, depending on which app you use) provided sleep advice.

The three staffers who helped us test all regularly use a wearable, and their opinions were mixed about whether they’d buy an additional sleep-tracking phone app. Our Garmin fan and tester said she’d stick with her wearable, because she “didn’t want to touch my phone for fear I’d screw it up.” Our Fitbit wearer said she’s interested in supplementing her tracking with a phone app. “I found it nice to have a reason to put my phone down instead of staring at it until I eventually doze off,” she said. She also appreciated the smart alarm. “It seemed to help me wake up less groggy.” Our Apple Watch wearer decided he didn’t see a need for a sleep tracker, whether on his watch or phone; he sleeps well without either.

What to look forward to

Sleep trackers are a work in progress. New apps come and often go; apps are constantly updated, and, in fact, many updates happened even over the course of our research. Fitness trackers are continually updating as well, and the Apple Watch has its own ever-changing array of tracking apps to choose from. As the field heats up, it’s reasonable to expect that the Apple Watch and other wearables, such as Samsung’s, will upgrade their sleep-tracking game. Suffice it to say, we’ll keep tracking the trackers, so expect updates down the road.

The competition

We couldn’t recommend Pillow for most people, because it’s available only for iOS, and it must be placed on your mattress (by your pillow—get it?) for it to work; if you don’t mind that, you might actually prefer this app over the others. It uses the phone’s accelerometer and gyroscope to track movement (along with sound-sensing technology and Apple Health data), presents about as much sleep information as SleepScore, and provides helpful sleep tips and lifestyle correlations, too. Although it regularly under-reported my wake time compared with the other apps, I was pleasantly surprised that the one time I woke up from a dream and jotted down the time, the app recorded REM sleep at roughly the same time, too. Unlike the other apps we tried, you can use it on the Apple Watch and it costs only a one-time payment of $5.

Sleep as Android has an enthusiastic following, with almost a quarter million reviews and a 4.3-star rating on Google Play. Nevertheless, I found the app, which gives you a choice between using motion detection on the bed or sonar on the nightstand, difficult to use and its readings hard to decipher. I did like the smart alarm, which won’t turn off unless you perform particular tasks designed to wake you up for good (such as shaking your phone or doing math problems). It’s also compatible with several wearables, including Garmin devices, and it integrates with Samsung Health and Google Fit. Sleep as Android offers a two-week free trial; after that, you can use it with all the bells and whistles but only every other day and with ads, or pay a one-time $6 fee for premium service (which includes extra charts and no ads). At week two (or beyond, depending on your sleep situation), the app will offer advice; we plan on long-term testing this app to assess the quality of the sleep recommendations.

Sources

Kelly Baron, PhD, associate professor of psychology, University of Utah School of Medicine, phone interview, August 6, 2018